Obesity is often associated with an impairment of the hypothalamic-pituitary-gonadal axis and also unites with reproductive defects and reduced fertility. The leptin-deficient ob/ob mouse is characterized by a morbid obesity and infertility. In the present study, we examined when ob/ob mouse lost their fertility activity according to aged dependent were investigated. The major organ systems in the body, the ovaries of females are the first to exhibit impaired function with advancing age. Here, ob/ob and ob lean various (4, 6, 9, 12 and 24 wks) aged mice were used. Histology (H & E staining) of ovary, vaginal smear and Reverse transcription polymerase chain reaction (RT-PCR) analysis were carried out. Hematoxylin/eosinstained sections show normal histology in ob lean type mice characterized by the presence of multiple primary and secondary follicles and well developed corpora lutea (CL). Ovaries from ob/ob mice, showed 4 and 6 wks mice similar to ob lean type but according to aged dependent ob/ob mice few primary and secondary follicles was seen. Many large empty follicles were present and no proper developed CL, especially 24 wks mice. Vaginal smear showed abnormal estrous cycle in ob/ob mice. Ovaries of ob/ob mice, mRNA results showed that ovulated gene TIMP1, Pgsh2 and Lhcgr expression levels are decreased according to aged dependent compared to ob lean type mice. These data suggest that aged dependent specifically when 24 wks of ob/ob mice lost their reproductive function.